Atmospheric dust levels are rising in the Great Plains
Dust increases reflect farming practices and climate trends reminiscent
of the lead-up to the 1930s Dust Bowl

Date:
October 13, 2020
Source:
University of Utah
Summary:
A study finds that atmospheric dust levels are rising across
the Great Plains at a rate of up to 5% per year. The trend of
rising dust parallels expansion of cropland and even seasonal crop
cycles. And if the Great Plains becomes drier, a possibility under
climate change scenarios, then all the pieces are in place for a
repeat of the Dust Bowl that devastated the Midwest in the 1930s.



FULL STORY ==========================================================================
Got any spaces left on that 2020 bingo card? Pencil in "another Dust Bowl
in the Great Plains." A study from University of Utah researchers and
their colleagues finds that atmospheric dust levels are rising across
the Great Plains at a rate of up to 5% per year.


==========================================================================
The trend of rising dust parallels expansion of cropland and seasonal
crop cycles, suggesting that farming practices are exposing more soil
to wind erosion. And if the Great Plains becomes drier, a possibility
under climate change scenarios, then all the pieces are in place for a
repeat of the Dust Bowl that devastated the Midwest in the 1930s.

"We can't make changes to the earth surface without some kind of
consequence just as we can't burn fossil fuels without consequences,"
says Andy Lambert, lead author of the study and a recent U graduate. "So
while the agriculture industry is absolutely important, we need to
think more carefully about where and how we plant." The research is
published in Geophysical Research Letters and was funded by the Utah
Science Technology and Research (USTAR) initiative, the Global Change
and Sustainability Center at the University of Utah, and the Associated Students of the University of Utah.

The first Dust Bowl In the 1930s, a drought blanketed the Great Plains,
from Mexico to Canada. This wouldn't have been such a big deal except that
in the 1920s Midwestern farmers had converted vast tracts of grassland
into farmland using mechanical plows.

When the crops failed in the drought the open areas of land that used
to be covered by grass, which held soil tightly in place, were now bare
dirt, vulnerable to wind erosion.



==========================================================================
"The result was massive dust storms that we associate with the Dust
Bowl," Lambert says. "These dust storms removed nutrients from the
soil, making it more difficult for crops to grow and more likely for
wind erosion to occur." After years of drought, dust and hardship,
rain finally began to fall again, bringing the Dust Bowl to a close.

"But the damage was already done to the soil," Lambert says. "Some areas
have still not fully recovered." Around the 2000s, the growth in demand
for biofuels spurred renewed expansion of farmland to produce the needed
crops. In an echo of the 1920s, this expansion replaced stable grasslands
with vulnerable soil. Over five years, from 2006 to 2011, 2046 square
miles (530,000 hectares) of grassland in five Midwestern states became
farmland -- an area a little smaller than Delaware.

At the same time, parts of the Great Plains experienced longer and
more severe droughts in the 20th century. The future of drought in
that region is, so far, uncertain, but the potential for a warmer,
drier Great Plains has Lambert and co-author Gannet Hallar, associate
professor of atmospheric sciences, bringing up the word "desertification"
in relation to the potential future of the region.

Eyes in the dusty skies The focus of the study by Lambert, Hallar and colleagues from the U, the University of Colorado-Boulder and Colorado
State University, was to quantify how much the amount of dust in the
atmosphere over the Great Plains had changed in recent decades. To do
that, they tapped into instrumentation that measures atmospheric haziness
from the ground up and from space down. From the ground, the IMPROVE
monitoring network is run by several federal agencies and measures the
amount of particulate matter in the air at sites, including national
parks, around the country. Another ground-based network, the NASA-run
AERONET, watches for how much incoming sunlight is blocked by dust and
aerosol particles in the air. From space, an instrument called MODIS
does the same job, looking at how much light reflected from the surface
is similarly blocked by particles.



==========================================================================
All together, the data cover years from 1988 to 2018. Dust, they found,
is increasing in the atmosphere over the whole of the Great Plains by
as much as 5% per year.

"The amount of increase is really the story here," Hallar says. "That 5%
a year over two decades, of course, is a hundred percent increase in
dust loading.

This is not a small signal to find." Correlating with crop timing The researchers further found correlations between dust in the atmosphere and
crop timings. In Iowa, where soybeans have been a major expanding crop, increases in dust appeared in June and October -- planting and harvesting months, respectively, for soybeans. In the southern Great Plains states,
where corn is a more dominant crop, dust increases appeared in March
and October - - again correlating to corn planting and harvesting seasons.

That was remarkable," Hallar says, "in the sense of how clear the
signal was." Are we seeing the beginnings of the second Dust Bowl?
"I think it's fair to say that what's happening with dust trends in the
Midwest and the Great Plains is an indicator that the threat is real
if crop land expansion continues to occur at this rate and drought risk
does increase because of climate change," Lambert says. "Those would be
the ingredients for another Dust Bowl." "This is an example of the need
for the agricultural community in the U.S. to think about adapting and mitigating to a changing climate," Hallar says. "So if we become more
arid we will need to think about the impacts of land degradation in that changed climate. What we did in the past isn't necessarily what we can
do in the future."

========================================================================== Story Source: Materials provided by University_of_Utah. Original written
by Paul Gabrielsen.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Andrew Lambert, A. Gannet Hallar, Maria Garcia, Courtenay Strong,
Elisabeth Andrews, Jenny L. Hand. Dust Impacts of Rapid Agricultural
Expansion on the Great Plains. Geophysical Research Letters, 2020;
DOI: 10.1029/2020GL090347 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201013124158.htm

--- up 7 weeks, 1 day, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)